Abstract
A new aseismatic asphalt mixture suitable for underwater construction has been developed, to be used for thin facing or lining of dams and other large-scale hydraulic structures. This mixture possesses sufficient fluidity for uniform spreading over specified area, even underwater. Furthermore, the hardened (in a room temperature) mixture would remain stable under large seismic load due to its elasticity similar to rubber, and would exhibit excellent water-tightnessand durability owing its compact molecular structure. The mixture consists of aggregates, fillers, and a special comprising mainly of bitumen. Tire chips were used as an aggregate to enable conservation of resources. A special coupling agent was used to avoid separation of the chips from the binder, and a viscosity reducing agent was used to lower manufacturing temperature approximately 30°C below the normal figure. As such, CO2 generated during production (hot mixing) is much less than usual. Since the spreading temperature of the mixture is below 100°C, safe underwater construction is possible. In addition, cost is reduced because of shorter construction period resulting from the thin working thickness (approximately 30mm). More than 25 years have passed since construction of most of the large-scale hydraulic structures in Japan, and they are awaiting extensive repair works. In addition to water-tightness, seismic resistivity is indispensable for repairing materials used in Japan where earthquakes frequently occur. The asphalt mixture developed for the study enables safe and prompt repair works through a totally new construction method taking into account seismic resistivity and environmental conservation, to be used even during services of dams.
